What does x= ? It doesn’t say.
namely how many times does ¼ go into 2, well that'd be 2 ÷ ¼,

Answer:
- 60<em><u>÷</u></em><em><u>15</u></em><em><u> </u></em><em><u>=</u></em><em><u>4</u></em><em><u> </u></em>
<em><u>Therefore</u></em><em><u> </u></em><em><u>Martin</u></em><em><u> </u></em><em><u>uses</u></em><em><u> </u></em><em><u>his</u></em><em><u> </u></em><em><u>power</u></em><em><u> </u></em><em><u>saw</u></em><em><u> </u></em><em><u>4</u></em><em><u> </u></em><em><u>times</u></em><em><u> </u></em><em><u>in</u></em><em><u> </u></em><em><u>one</u></em><em><u> </u></em><em><u>hour</u></em><em><u> </u></em>
Hello,
Use the factoration
a^2 - b^2 = (a - b)(a + b)
Then,
x^2 - 81 = x^2 - 9^2
x^2 - 9^2 = ( x - 9).(x + 9)
Then,
Lim (x^2- 81) /(x+9)
= Lim (x -9)(x+9)/(x+9)
Simplity x + 9
Lim (x -9)
Now replace x = -9
Lim ( -9 -9)
Lim -18 = -18
_______________
The second method without using factorization would be to calculate the limit by the hospital rule.
Lim f(x)/g(x) = lim f(x)'/g(x)'
Where,
f(x)' and g(x)' are the derivates.
Let f(x) = x^2 -81
f(x)' = 2x + 0
f(x)' = 2x
Let g(x) = x +9
g(x)' = 1 + 0
g(x)' = 1
Then the Lim stay:
Lim (x^2 -81)/(x+9) = Lim 2x /1
Now replace x = -9
Lim 2×-9 = Lim -18
= -18